Flexible couplings are often used to connect two aligned, rotatable shafts for transmitting power from the driving shaft to the driven shaft. In general, the couplings have two similar halves, each mounted on the opposed ends of the respective shafts, and are connected by a flexible element of rubber or other elastomeric material. The flexible element transmits the torque developed by the driving shaft to the driven shaft and also permits the coupling to accommodate slight amounts of angular and/or parallel misalignment of the shafts, and also end float, as manifested by the shafts during operation. Thus, the connecting element must be sufficiently flexible to tolerate slight variances from perfect shaft alignment, yet sufficiently rigid to effectively transmit power. Due to its function in the coupling, the flexible element is subjected to a high degree of stress, and thus is subject to failure through tearing or other separations. Such failures are not uncommon; thus, many flexible couplings have been designed with a split, flexible element secured by external clamp members so that a failed element may be replaced without dismantling the entire coupling. The clamp members are merely removed, the element spread open at the slit and placed in position around the coupling, and the clamp members are then replaced.
During operation of the machinery on which the coupling is mounted, centrifugal force, produced by the rotating coupling assembly, tends to force the flexible element into a prabolic shape. This places extreme stress on the element, especially at the locus of clamping. In addition, during start-up operations or where severe shock loads, such as frequent reversals, must be handled by the coupling, even greater stress may be placed on the flexible element due to the high levels of torque generated. Flexible coupling elements are often reinforced with layers of fabric or cord interspersed in the elastomeric material. This practice adds strength to the coupling element; however if, improperly manufactured or bonded. The layers are subject to separation, with consequent failure of the element.